1. Field of the Invention
The present invention relates to 1,14-bis(4-nitrophenyl)-1,3,5,7,9,11,13-tetradecaheptaene and a method of preparing the same, which serves as a starting or intermediate material for preparing a bisazo compound which is effective as an organic photoconductive material for use in electrophotography.
2. Discussion of Background
It is conventionally known that particular azo compounds effectively serve as organic photoconductive materials for use in electrophotography, especially as charge generating materials for use in a two-layered type electrophotographic photoconductor. The two-layered type electrophotographic photoconductor is constructed in such a manner that (i) a charge generation layer comprising a charge generating material capable of generating charge carriers when exposed to light and (ii) a charge transport layer comprising a charge transporting material capable of performing efficient injection and transportation of the above-mentioned charge carriers are successively overlaid on an electroconductive support.
The azo compounds, which are conventionally used as the charge generating materials in the electrophotographic photoconductor, are, for example, benzidine type bisazo compounds as disclosed in Japanese Laid-Open Patent Applications 47-37543 and 52-55643 stilbene type bisazo compounds in Japanese Laid-Open Patent Application 52-8832; diphenylhexatriene type bisazo compounds in Japanese Laid-Open Patent Application 58-222152; and diphenylbutadiene type bisazo compounds in Japanese Laid-Open Patent Application 58-222153.
The photosensitivities of the two-layered type electrophotographic photoconductors using the above azo compounds as charge generating materials, however, are usually not high, so that such photoconductors are not always suitable for use in a high-speed copying apparatus.
In accordance with the recent development of laser printers, a demand for a photoconductor having high photosensitivity in the wavelength range of semiconductor laser is increasing. The above conventional two-layered electrophotographic photoconductors, however, do not necessarily satisfy all the requirements for the photoconductor for use in laser printers.